Improvement of water management in polymer electrolyte membrane fuel cell thanks to cathode cracks

Karst, N.; Faucheux, Vincent; Martinent, Audrey; Bouillon, Pierre; Simonato, Jean‐Pierre

doi:10.1016/j.jpowsour.2010.03.025

Cited by 25 publications

(14 citation statements)

References 23 publications

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“…35 A few papers, on the other hand, report that crack formation can also benefit the cell performance by facilitating the access of gaseous reactants to the reaction site. 36,37 It should be noted that the pinhole formation and the improved gaseous reactant access through crack formation mentioned in literature is consistent with our observations with LSC-W/A and SSC-W/A MEAs. Also, the detrimental impact of the macro-scale cracks on PEM durability seems to be consistent in agreement with our research.…”

Section: Pem Degradation Mechanism-pem Thinning Vs Pinholesupporting

confidence: 92%

The Effect of Cathode Structures on Nafion Membrane Durability

Choi

Langlois

Mack

et al. 2014

J. Electrochem. Soc.

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The effect of cathode structures on the chemical stability of Nafion membranes is investigated. Membrane electrode assemblies (MEAs) were prepared by using Nafion 212 membrane and commercially available carbon supported Pt electro-catalysts. The cathode structures were controlled by the use of long side chain (LSC) and short side chain (SSC) perfluorosulfonic acids (PFSAs) as well as three dispersing solvents for the electrode fabrication (a water-isopropanol mixture, N-methyl-2-pyrrolidone, or glycerol). The membrane durability was evaluated by the H 2 crossover current density after a 200-hour open circuit voltage accelerated stress test. The MEA with a glycerol-processed SSC PFSA-bonded cathode exhibited a 200-fold less H 2 crossover current density than the MEA with a water-isopropanol-processed LSC PFSA-bonded cathodes. The analyzes by electrochemical impedance spectroscopy and microscopy suggest that the structural uniformity of cathodes play the most significant role in the chemical stability of the Nafion membranes. This study emphasizes the importance of cathode structures on the durability of Nafion membranes. Polymer electrolyte membranes (PEMs) are a critical cell component for polymer electrolyte membrane fuel cells (PEMFCs). The durability of PEMs are important because the life of PEMFCs is often determined by PEM failure.1 The chemical stability of PEMs have been discussed since the 1960s, notably by engineers and scientists at GE.2 LaConti proposed a chemical degradation mechanism for perfluorosulfonic acids (PFSAs):3 oxygen molecules permeate through the membrane from the cathode and are reduced at the anode Pt catalyst to form hydrogen peroxide. Although PFSA membranes are stable in the presence of hydrogen peroxide, metal ions such as Fe 2+ and Cu 2+ in the catalyst layers greatly accelerate the membrane degradation rate by forming reactive oxygen species such as hydroxyl (HO·) and hydroperoxyl (HO 2 ·) radicals.Since the reactive oxygen species are generated in the catalyst layer, the membrane degradation is greater with a supply of H 2 and O 2 in the catalyst layers. Liu et al. reported about the substantially short lifetime for Nafion membranes when H 2 and O 2 gases were supplied to the catalyst-coated membrane, while no degradation is detected when H 2 /O 2 is decoupled to H 2 /N 2 or N 2 /O 2 .7 Later, Burlatsky et al. suggested that an extended catalyst layer between the cathode and the membrane could consume reactive oxygen species to produce water, thereby mitigating the membrane degradation. 8 The effect of gas permeability on membrane degradation has been also demonstrated. Sethuraman et al. compared the durability of wholly aromatic membranes, BPSH-35 and Nafion 112, under accelerated stress conditions. 9 Although the BPSH-35 membranes showed poor chemical stability in ex-situ Fenton tests, the membrane electrode assemblies (MEAs) Because the chemical degradation of membranes is related to the formation of reactive oxygen species in the catalyst layers and their access throug...

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Section: Pem Degradation Mechanism-pem Thinning Vs Pinholesupporting

confidence: 92%

The Effect of Cathode Structures on Nafion Membrane Durability

Choi

Langlois

Mack

et al. 2014

J. Electrochem. Soc.

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“…Another possible DMFC degradation mode is electrode micro-cracking. While in general adversely impacting DMFC performance through a buckling deformation [24], pin-hole formation in the membrane [25], inhibiting multi-phase transport [26], and affecting the three-phase interface regions [27], the crack formation can also benefit the cell performance by facilitating access of reactants to the reaction site [28,29]. As a result, the overall effect of the catalyst layer cracks on the DMFC durability is not obvious.…”

Section: Introductionmentioning

confidence: 99%

Micro-crack formation in direct methanol fuel cell electrodes

Li¹,

Spernjak²,

Zelenay³

et al. 2014

Journal of Power Sources

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This study focuses on the micro-crack formation of Nafion ® -based membrane electrode assemblies (MEAs) after extended direct methanol fuel cell (DMFC) operation. All electrodes, both with metal-black and carbon-supported catalysts, contain some microcracks initially; the area covered by these cracks increases both in the anode and cathode after 100-hours of DMFC test. X-ray tomography shows an increase in the crack area in both anode and cathode that correlates with methanol feed concentration and methanol crossover. The MEAs with carbon-supported catalysts and thicker membrane are more resistant to the formation of micro-cracks compared to those with metal-black catalysts and thinner membrane, respectively. The impact of the micro-crack formation on cell performance and durability is limited over the 100-hour DMFC operation, with the longterm impact remaining unknown.

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“…The benefits of the cracks on the performances have been investigated by another study [Karst et al, 2010]. The limit between benefits and drawbacks can be developed by controlling cracks formation.…”

Section: Resultsmentioning

confidence: 99%

“…Consequently, the catalyst layer structure was a major parameter on the fuel cell performances. Cathode cracks have already been investigated [Karst et al, 2010]. Cell drying and flooding were decreased in a cathode catalytic layer with 8 % of its surface covered by cracks compared to a non-cracked continuous cathode.…”

Section: Influence Of the Microstructure On The Electrochemical Propementioning

confidence: 99%

Proton Exchange Membrane Fuel Cell

Taner¹

2018

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Improvement of water management in polymer electrolyte membrane fuel cell thanks to cathode cracks

Cited by 25 publications

References 23 publications

The Effect of Cathode Structures on Nafion Membrane Durability

The Effect of Cathode Structures on Nafion Membrane Durability

Micro-crack formation in direct methanol fuel cell electrodes

Proton Exchange Membrane Fuel Cell

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